1. Field of the Invention
Structural design for a universal cavity pit wrench, more specifically that of a wrench or spanner capable of loosening or tightening up screw nuts or operations involving such loosening or tightening effects without directional restrictions executed against nut bearing cavities of any configurations mounted with a plurality of freely retractable pillar posts.
2. Description of the Prior Art
Conventional art for cavity pit wrenches is typically represented by those devices which are adapted specifically to work on hexagonal cavity pit nuts. The dimension of each hexagonal cavity pit nut that corresponds to a hexagonal pillar spanner of a corresponding dimension is chosen to match, to loosen or tighten up an object nut, and this necessitates the user to bring with him a lot of pillar wrenches of different sizes to meet the demand for working with cavity pit nuts of differing sizes. A common practice among the manufacturers is to assemble the pillar spanners in a set for portable handling, but such execution is still not convenient. Further, the size insufficiency can still be a problem all the same, and improvement is still being sought after; while on the other hand, where the nut set in the cavity pit bears a profile other than hexagonal, petal or polygonal, for example, then the conventional hexagonal pillar spanner can do nothing at all, and the user will have to get a specifically configured cavity pit spanner to go ahead with loosening or tightening up operations for the non-hexagonal, petal or polygonal nuts. In the prior art, where a different, unforeseen pattern of cavity pit nut or one bearing a different size is encountered, a correspondingly shaped cavity pit spanner will have to be prepared in order to get the job done, and that necessarily brings about increased need for more supply of more varieties of spanner tools, giving occasion to more chances of confusion and the shortage of such tools is still inevitable from case to case.
In U.S. Pat. Nos. 5,644,959, 5,386,749, and 5,460 064, and similar patents provide, altogether, various multi-purpose wrench designs, but they apply uniquely and only to protrusive type nuts, none of them caters to cavity pit type nuts at all.
The primary object of the invention, therefore, is to provide a structural design of a universal cavity pit type wrench or spanner, comprising essentially: a sleeving, a mounting panel, a plurality of pillar posts, retainer rods and a number of correspondingly functioning retraction springs, with the plurality of pillar posts being aligned and mounted on top of the sleeving, they, so arranged and endowed with retractable effects, stemmed against the nut bearing cavity pits, are able to drive the nuts as set in the cavity pits to loosen off or contrarily to tighten up, and that means then that one single stereotyped universal spanner will suffice to work on a cavity set nut of one out of quite a number of cavity configuration or sizes, in all conveniences relieving the user of the nuisance of switching to another tool while working on different specifications of cavity set nuts.
A further object of the invention lies in the provision of the structural design for a universal cavity pit spanner wherein the plurality of pillar posts are preferably processed to be polygonal or to yield a thinner diameter, so that once inserted by retraction into the nut bearing pit, a firm, tight-set plunging effect is assured, whereby yet simpler and more reliable application of force with respect to the nut at work is readily achievable.